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• FFmpeg remuxing parts of an audio file

  22 décembre 2022, par zorleone

  I'm trying to remux individual tracks from a FLAC file using the FFmpeg libraries.
I get the starting timestamps from a Cue sheet, I seek to the timestamps using avformat_seek_file. However after writing the packets to output files, they only have data from the beginning of the input file.

  


  This is the code snippet which opens the input FLAC and also creates an output AVFormatContext for each track. I'm guessing the issue is avformat_seek_file, it doesn't seem to do anything, since even though I seek to the beginning of a track, the output file contains data from the beginning of the input.

  


      for(int i = 0; i <= sheet.ntracks; i++) {
        sheet.avfmtctx = avformat_alloc_context();
        if(avformat_open_input(&sheet.avfmtctx, sheet.file, NULL, NULL) < 0) {
            fprintf(stderr,
                    "avformat_open_input(): failed to open %s\n",
                    sheet.file);
            return 1;
        }
        int audio_stream_idx = -1;
        for(int i = 0; i < sheet.avfmtctx->nb_streams; i++) {
            if(sheet.avfmtctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
                audio_stream_idx = i;
                break;
            }
        }
        avformat_find_stream_info(sheet.avfmtctx, NULL);
        AVFormatContext *output;
        char *filepath = title_to_filepath(&sheet.tracks[i], sheet.file);
        avformat_alloc_output_context2(&output, NULL, NULL, filepath);
        AVStream *out_audio_stream = avformat_new_stream(output, NULL);
        avcodec_parameters_copy(out_audio_stream->codecpar,
                                sheet.avfmtctx->streams[audio_stream_idx]->codecpar);

        if(avio_open(&output->pb, filepath, AVIO_FLAG_WRITE) < 0) {
            fprintf(stderr, "Failed to open %s for writing\n", filepath);
            return 1;
        }
        if(avformat_write_header(output, NULL) < 0) {
            fprintf(stderr, "avformat_write_header() failed\n");
            return 1;
        }
        int64_t current_frame = sheet.tracks[i].index;
        int64_t next_track_index = (i < sheet.ntracks) ?
                                   sheet.tracks[i + 1].index :
                                   INT64_MAX;
        if(avformat_seek_file(sheet.avfmtctx,
                           -1,
                           INT64_MIN,
                           current_frame,
                           current_frame,
                           0) < 0) {
            fprintf(stderr, "Failed to seek to the index of track %d\n", i);
            avformat_free_context(sheet.avfmtctx);
            sheet.avfmtctx = NULL;
            av_write_trailer(output);
            avio_closep(&output->pb);
            avformat_free_context(output);
            free(filepath);
            continue;
        }
        AVPacket *pkt = av_packet_alloc();
        int64_t pts_diff = AV_NOPTS_VALUE, dts_diff = AV_NOPTS_VALUE;
        while(current_frame < next_track_index && !avio_feof(output->pb)) {
            int ret;
            if((ret = av_read_frame(sheet.avfmtctx, pkt)) < 0) {
                if(ret != AVERROR_EOF)
                    fprintf(stderr, "av_read_frame() failed: %s\n", av_err2str(ret));
                break;
            }
            if(pkt->stream_index != audio_stream_idx)
                continue;
            // runs only once
            if(pts_diff == AV_NOPTS_VALUE && dts_diff == AV_NOPTS_VALUE) {
                pts_diff = pkt->pts;
                dts_diff = pkt->dts;
            }

            pkt->stream_index = 0; // first and only stream
            pkt->pts -= pts_diff;
            pkt->dts -= dts_diff;
            pkt->pos = -1;
            av_interleaved_write_frame(output, pkt);

            current_frame++;
        }

        avformat_free_context(sheet.avfmtctx);
        sheet.avfmtctx = NULL;

        av_write_trailer(output);
        av_packet_free(&pkt);
        avio_closep(&output->pb);
        avformat_free_context(output);

        free(filepath);
    }



  


  current_frame and next_track_index are calculated from the INDEX lines in the Cue sheet : MM * 60 * 75 + SS * 75 + FF.
Can someone tell me what I'm doing wrong, and how to get the data I need from the input ?

  


• I cannot find any way to convert multiple jpg or png to gif in vb.net using ffmpeg

  4 juillet 2017, par Silvia Fonseca

  Is there anyway i can get multiples png or jpg images to gif using ffmpeg in vb.net
  I have start a new application to capture certain frames from a video but now i want to get all the frames extracted in gif image using ffmpeg.
  This is my code so far :
  I have in fact all ready try like this but not succeed
  I have made some changes and i get the gif file but in empty state
  This is my code so far

  Imports System.Diagnostics
  
  Imports System.ComponentModel
  
  Imports System
  
  Imports System.IO
  
  Public Class Form1
  
  Dim video = ""
  
  Dim startInfo As New ProcessStartInfo("ffmpeg.exe")
  
  Dim frame As Long 'individual frames
  
  Dim tempdir As String = "C:\avitogifconverter\" ' images temp directory
  
  Dim DestPath As String = "C:\avitogifconverter\"
  
  Public Declare Auto Function FindWindowNullClassName Lib "user32.dll" Alias "FindWindow" (ByVal lpClassname As Integer, ByVal lpWindownName As String) As Integer
  
  Dim Counter As Integer = 0
  
  
  
  Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
  
      My.Computer.FileSystem.CreateDirectory(tempdir)
  
      TextBox1.Text = "exp:-->video.avi or webm or flv"
  
      TextBox1.Clear()
  
  
  
  
  
  
  
  End Sub
  
  
  
  
  
  Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
  
      Dim p As Process = Process.Start("cmd", "/k ffmpeg.exe -i " + TextBox1.Text + " -filter:v fps=1/15 C:\avitogifconverter\out%02d.jpg")
  
      p.WaitForExit()
  
  
  
      If p.HasExited Then
  
          MsgBox("The Extraction Are Finish...")
  
      End If
  
  
  
  End Sub
  
  
  
  Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
  
  
  
  End Sub
  
  
  
  Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
  
      Label3.Text = "cmd" + "/k ffmpeg.exe -i " + TextBox1.Text + " -filter:v fps=1/15 C:\avi to gif converter\out%02d.jpg"
  
  End Sub
  
  
  
  Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
  
  
  
  
  
      If (OpenFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK) Then
  
          'TextBox1.Text = OpenFileDialog1.FileName
  
          TextBox1.Text = System.IO.Path.GetFileName(OpenFileDialog1.FileName)
  
      End If
  
      If TextBox1.Text = Nothing Then
  
          Return
  
      End If
  
      If TextBox1.Text <> Nothing Then
  
          'My.Computer.FileSystem.CopyFile(TextBox1.Text, DestPath)
  
      End If
  
  
  
  End Sub
  
  
  
  Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
  
      Dim args As String 'declare args
  
      args = " -framerate 1/5 -i C:\avitogifconverter\out%02d.jpg -c:v libx264 -r 30 -pix_fmt yuv420p C:\avitogifconverter\out.gif "
  
      Dim proc As New Process
  
      Dim proci As New ProcessStartInfo
  
      proci.FileName = My.Application.Info.DirectoryPath & "\ffmpeg.exe"
  
      proci.Arguments = args
  
      proci.WindowStyle = ProcessWindowStyle.Hidden
  
      proci.CreateNoWindow = True
  
      proci.UseShellExecute = False
  
      proc.StartInfo = proci
  
      proc.Start()
  
      Do Until proc.HasExited = True
  
          Me.Text = "Saving"
  
      Loop
  
      Me.Text = "your video done"
  
  
  
      MsgBox("Done")
  
  
  
      'IO.Directory.Delete(tempdir, True)
  
  End Sub
  
  End Class

• arm : vp9itxfm : Skip empty slices in the first pass of idct_idct 16x16 and 32x32

  9 janvier 2017, par Martin Storsjö

  arm : vp9itxfm : Skip empty slices in the first pass of idct_idct 16x16 and 32x32
  This work is sponsored by, and copyright, Google.
  Previously all subpartitions except the eob=1 (DC) case ran with
  
  the same runtime :
                                       Cortex A7       A8       A9      A53
  
  vp9_inv_dct_dct_16x16_sub16_add_neon :   3188.1   2435.4   2499.0   1969.0
  
  vp9_inv_dct_dct_32x32_sub32_add_neon :  18531.7  16582.3  14207.6  12000.3
  By skipping individual 4x16 or 4x32 pixel slices in the first pass,
  
  we reduce the runtime of these functions like this :
  vp9_inv_dct_dct_16x16_sub1_add_neon :     274.6    189.5    211.7    235.8
  
  vp9_inv_dct_dct_16x16_sub2_add_neon :    2064.0   1534.8   1719.4   1248.7
  
  vp9_inv_dct_dct_16x16_sub4_add_neon :    2135.0   1477.2   1736.3   1249.5
  
  vp9_inv_dct_dct_16x16_sub8_add_neon :    2446.7   1828.7   1993.6   1494.7
  
  vp9_inv_dct_dct_16x16_sub12_add_neon :   2832.4   2118.3   2266.5   1735.1
  
  vp9_inv_dct_dct_16x16_sub16_add_neon :   3211.7   2475.3   2523.5   1983.1
  
  vp9_inv_dct_dct_32x32_sub1_add_neon :     756.2    456.7    862.0    553.9
  
  vp9_inv_dct_dct_32x32_sub2_add_neon :   10682.2   8190.4   8539.2   6762.5
  
  vp9_inv_dct_dct_32x32_sub4_add_neon :   10813.5   8014.9   8518.3   6762.8
  
  vp9_inv_dct_dct_32x32_sub8_add_neon :   11859.6   9313.0   9347.4   7514.5
  
  vp9_inv_dct_dct_32x32_sub12_add_neon :  12946.6  10752.4  10192.2   8280.2
  
  vp9_inv_dct_dct_32x32_sub16_add_neon :  14074.6  11946.5  11001.4   9008.6
  
  vp9_inv_dct_dct_32x32_sub20_add_neon :  15269.9  13662.7  11816.1   9762.6
  
  vp9_inv_dct_dct_32x32_sub24_add_neon :  16327.9  14940.1  12626.7  10516.0
  
  vp9_inv_dct_dct_32x32_sub28_add_neon :  17462.7  15776.1  13446.2  11264.7
  
  vp9_inv_dct_dct_32x32_sub32_add_neon :  18575.5  17157.0  14249.3  12015.1
  I.e. in general a very minor overhead for the full subpartition case due
  
  to the additional loads and cmps, but a significant speedup for the cases
  
  when we only need to process a small part of the actual input data.
  In common VP9 content in a few inspected clips, 70-90% of the non-dc-only
  
  16x16 and 32x32 IDCTs only have nonzero coefficients in the upper left
  
  8x8 or 16x16 subpartitions respectively.
  This is cherrypicked from libav commit
  
  9c8bc74c2b40537b0997f646c87c008042d788c2.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/arm/vp9itxfm_neon.S
  • [DH] tests/checkasm/vp9dsp.c